title: Electrochemical immunosensors for cancer biomarker with signal amplification based on ferrocene functionalized iron oxide nanoparticles.
abstract: Ultrasensitive sandwich type electrochemical immunosensors for the detection of cancer biomarker prostate specific antigen (PSA) is described which uses graphene sheet (GS) sensor platform and ferrocene functionalized iron oxide (Fe(3)O(4)) as label. To fabricate the labels, dopamine (DA) was first anchored onto Fe(3)O(4) surface followed by conjugating ferrocene monocarboxylic acid (FC) and secondary-antibody (Ab(2)) onto Fe(3)O(4) through the amino groups of DA (DA-Fe(3)O(4)-FC-Ab(2)). The great amount of DA molecules anchored onto Fe(3)O(4) surface increased the immobilization of FC and Ab(2) onto the Fe(3)O(4) nanoparticle, which in turn increased the sensitivity of the immunosensor. GS used as biosensor platform increased the surface area to capture a great amount of primary antibodies (Ab(1)) and the good conductivity of GS enhanced the detection sensitivity to FC. Using the redox current of FC as signal, the immunosensor displays high sensitivity, wide linear range (0.01-40 ng/mL), low detection limit (2 pg/mL), good reproducibility and stability. In addition, this method could be extended to the immobilization of other interesting materials (fluorescence dyes) onto Fe(3)O(4) for preparing various kinds of labels to meet the different requirements in immunoassays.
authors.affiliation: School of Medical and Life Sciences, University of Jinan, Jinan 250022, PR China. lihecd@gmail.com
authors.forename: He
authors.initials: H
authors.lastname: Li
authors.forename: Qin
authors.initials: Q
authors.lastname: Wei
authors.forename: Jing
authors.initials: J
authors.lastname: He
authors.forename: Ting
authors.initials: T
authors.lastname: Li
authors.forename: Yanfang
authors.initials: Y
authors.lastname: Zhao
authors.forename: Yanyan
authors.initials: Y
authors.lastname: Cai
authors.forename: Bin
authors.initials: B
authors.lastname: Du
authors.forename: Zhiyong
authors.initials: Z
authors.lastname: Qian
authors.forename: Minghui
authors.initials: M
authors.lastname: Yang
mesh_terms: D015374:Biosensing Techniques / Q000379:methods*; D004298:Dopamine / Q000737:chemistry; D055664:Electrochemical Techniques; D005290:Ferric Compounds / Q000737:chemistry*; D005296:Ferrous Compounds / Q000737:chemistry; D006801:Humans; D007118:Immunoassay; D008297:Male; D000075163:Metallocenes; D053758:Nanoparticles / Q000737:chemistry*; D017430:Prostate-Specific Antigen / Q000097:blood*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D005290:Ferric Compounds; D005296:Ferrous Compounds; D000075163:Metallocenes; C000499:ferric oxide; D017430:Prostate-Specific Antigen; C004998:ferrocene; D004298:Dopamine